Wind Power 2008, Houston: DNV is leading the way in helping the wind power industry to improve the quality and damage tolerance of wind turbine blades. A new Recommended Practice is under development.
“When producing increasingly larger fibre composite turbine blades the wind power industry is facing major challenges of consistent quality and sufficient robustness,” says Christer Eriksson, head of section at DNV in Denmark.
A major concern in the wind power industry is the long time it takes to establish internationally recognised standards. DNV is therefore launching a Joint Industry Project (JIP) to develop a Recommended Practice for defects and damage in composite structures and components. This will initially be based on existing knowledge drawn from various industries using large-scale structures made of composites, ranging from naval ships to aircraft.
“The Recommended Practice will contain a catalogue of production defect types and observed in-service damage. Further, the document will show how production defects can be minimised and how their consequences, and those of in-service damage, can be assessed and mitigated,” Brian Hayman explains.
“A further step is to develop a systematic approach for ensuring an adequate level of damage tolerance of wind turbine blades by a combination of material selection, structural design, production process control, testing and inspection. This subject was addressed at a recent international workshop in Denmark, attended by representatives of major manufacturers, research institutions and testing laboratories worldwide,” says Brian Hayman, senior principal engineer and composites expert at DNV.
Supplementing the wind turbine blade standard
The approaches developed in the Recommended Practice will supplement the DNV Offshore Standard DNV-OS-J102, first issued in October 2006, which covers design and manufacture of wind turbine blades for both offshore and onshore applications.
DNV-OS-J102 describes a systematic approach to manufacturing control. It is explained how critical issues in manufacturing are identified and controlled in a design process. The standard consolidates the vast amount of international experience present in the wind industry, and provides a basis for the blade designs of the future.
The standard is a key document in DNV Type Certification according to the IEC WT01 certification scheme. The standard clearly explains the relevant documentation that shall be issued by the blade designer in a certification process.
The organisation of the requirements in the standard allows generic issues in material qualification and design analysis to be cleared between the designer and the certifier in the first part of the certification process. This allows for a smooth and efficient approval process for the detailed design. The standard provides the user with access to unique knowledge in the design and manufacturing of wind turbine blades.
DNV’s role in establishing standards
DNV is a global provider of risk management services, helping customers to safely and responsibly improve their business performance. DNV is an independent foundation with the purpose of safeguarding life, property and the environment. Through its network of 300 offices in 100 countries, the company serves a range of industries, with a special focus on the maritime and energy sectors, combining its technology expertise with its industry knowledge.
Due to DNV’s in-depth knowledge and role as independent partner, we facilitate a great number of joint industry projects each year, many of them aimed specifically at developing standards. Our role for 143 years has been to assist in solving the challenges faced by business and society. Developing new tools, methodologies, standards, and recommended practices together with industry and authorities is exactly about solving these challenges.
DNV has considerable expertise in wind energy and is the world’s leading provider of services to the wind power industry, with main offices located in Seattle, USA and Copenhagen, Denmark.